Read this before buying a HEPA AC filter for your home or business
Chances are, you have been hearing a lot about HEPA AC filters and HVAC filters as a solution for preventing the transmission of COVID. The idea got a lot of media attention here in New York after Governor Andrew Cuomo spoke about using HVAC HEPA filters in malls to prevent airborne spread of the disease.
Here’s what you probably don’t know: there are downsides to using HEPA filters in your HVAC system.
We have been receiving many requests from homeowners and business owners in New York City to install HEPA AC filters. However, our experience, expertise, and integrity prohibit us from automatically providing what may appear to be a solution, yet could potentially result in costly system breakdowns and repairs.
Here’s what you need to know.
What HEPA AC filters do
A HEPA (high efficiency particulate air) filter is a thick, dense filter that is designed to capture tiny particles in the air passing through it, including pollutants and allergens.
HEPA filters can capture 99.97% of particles as small as .3 microns (the average cross section of a human hair is 50 microns) in size. That means HEPA filters do a great job of capturing particles like dust mites (100 – 300 microns), pollen (10 – 1000 microns), and even bacteria (1 – 10 microns). Viruses (including the COVID virus) can be much smaller than .3 microns, but HEPA AC filter can capture them because airborne particles are typically attached to larger “droplets” produced when someone coughs or sneezes.
Why a HEPA AC filter may NOT be a useful COVID mitigation solution
1. HEPA filters can’t trap all COVID-19 virus particles.
One problem is, any filter can only trap particles that pass through it. If an infected person coughs in your space with others nearby, particles in the air can transmit the disease before they ever have the chance to reach the HEPA filter. So you cannot be sure the occupants of your space are protected.
And there are other reasons why installing HEPA AC filters is not an appropriate solution for COVID:
2. Your system probably can’t accommodate a HEPA AC filter.
A HEPA AC filter is typically between 5 inches and 8 inches thick. Light commercial and residential air conditioning systems are designed to use much thinner filters. The filter housing typically can’t hold a 5 to 8 inch HEPA filter. So you’ll need modifications to your system if you want to install them, which can be expensive (especially for commercial systems with multiple filters).
3. HVAC HEPA filters can decrease performance and cause breakdowns.
Because HEPA filters are so dense, your system’s fan probably won’t have enough horsepower to pull air through the filter. Without that, the internal pressure drop across the filter can cause a strain on the system. Decreased airflow may mean your system can’t cool as well. It will need to run longer to reach set temperature. That uses more electricity, increases wear on parts, and can lead to more serious component failures.
4. HEPA filters are expensive.
HEPA filters can cost several hundred dollars each compared to a standard size MERV 8 filter which will cost approximately $5.50 each or a MERV 13 filter which will cost approximately $17 each. And because they remove more dust and debris from the air, you’ll need to change them more often.
Alternative COVID mitigation options
As most people know by now, the most effective tactics for preventing the spread of COVID are handwashing, social distancing, and wearing a mask. However, these additional tactics can help eliminate virus particles that may make their way into your HVAC system.
MERV 13 filters offer some protection, with less expense
“MERV” is a rating system for HVAC and other filters. The higher the MERV rating value on a filter, the smaller the particle it can capture, and with greater efficiency. Standard HVAC air filters used in most commercial and residential properties are rated at MERV 8. HEPA filters are rated between MERV 17 and MERV 20.
If you are concerned about indoor air quality above and beyond preventing COVID transmission, we recommend MERV 13 filters. This advice is based on recommendations from the CDC and ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers).
MERV 13 filters offer some protection and can capture 50% of particles in the size range of COVID particles. And they can definitely cut down on dust and allergens. More HVAC filter housings can accommodate them (but not all), and they are far less expensive than HEPA filters (although still 3 times the cost of standard MERV 8 filters). There may still be issues to consider with regard to airflow and performance with some HVAC systems, so always consult with HVAC professionals before buying them so you fully understand the cost and the potential benefit.
One caveat: as you might expect given the circumstances, demand is very high for MERV 13 filters. We are currently experiencing 6 to 8 week lead times and it’s likely to get worse before it gets better.
UV light technology keeps HVAC surfaces clean
You may have heard that ultraviolet (UV) light can deactivate coronavirus particles. UV air purifiers, when installed inside your HVAC system, can help to kill particles (including viruses, bacteria, and mold) that may accumulate on system components. They work particularly well to keep AC evaporator coils clean. That’s helpful because clean coils keep your system running effectively and efficiently, and can decrease the cost of ongoing maintenance.
Unfortunately, UV lights don’t work as well at destroying airborne particles inside an HVAC system. That’s because particles need to remain in the UV light’s “kill zone” long enough to be destroyed. Inside an HVAC system, fans typically are moving the air too quickly to kill airborne contaminants.
Advanced oxidation and ionization technology cleans the air
These types of air purifiers can help to remove airborne virus particles (and other contaminants) within your HVAC system. They are installed in a plenum, which is an air distribution chamber between the structural ceiling and drop ceiling, that’s connected to your ductwork.
The technology takes oxygen molecules from the air and converts them into charged atoms that then cluster around microparticles, surrounding and deactivating harmful substances like airborne mold, bacteria, allergens, and viruses. The larger particles result in more efficient filtering of the air. The process also produces friendly oxidizers found in nature that get distributed throughout your space, not only within your HVAC system. They have also been proven effective at reducing harmful VOCs and odors.
A combination of this technology along with upgraded MERV 13 filters will provide a much improved indoor air environment.
These solutions aren’t right for every situation, but can be extremely helpful in the right setting. And they can provide peace of mind for business owners who want to do everything they can to protect their employees and customers.
If you’re in the New York City metro area, contact Arista to learn more about these solutions and how they might help to protect your space.
More answers to your questions about HVAC and COVID transmission
Read this article to get the answers to common questions about COVID transmission and HVAC mitigation strategies.